It is a well known technique to bond together a pair of opposed bonding surfaces using an adhesive such as an instantaneous, photocurable, or hot melt adhesive. An adhesive is applied onto one or both of the bonding surfaces, and the adhesive wetting the surfaces is cured thereby progressing adhesion between the pressure-bonded surfaces.
Wettability of the bonding surfaces for an adhesive depends on the chemical properties (for example, hydrophilicity, hydrophobicity, and surface energy) of the bonding surfaces and the adhesive. Therefore, if the materials of bonding surfaces are different or the bonding surfaces are composed of fluorocarbon materials, the bonding surfaces have insufficient wettability for an adhesive. Accordingly, in such cases, it is difficult to achieve hermetic adhesion using an adhesive.
Electronic components such as semiconductor devices, image sensors, line sensors, liquid crystal displays (LCDs), plasma display panels (PDPs), and electroluminescence (EL) displays must be sealed in packages to prevent degradation by penetration of water. These electronic components requires bonding of surfaces composed of different materials. As described above, in such cases, sufficient hermeticity cannot be achieved with an adhesive, so that a welding method (for example, see Patent Document 1), a solder sealing method (for example, see Patent Document 2), or a low melting point glass sealing method (for example, see Patent Document 3) is used.    Patent Document 1: Japanese Unexamined Patent Application Publication No. 5-174733    Patent Document 2: Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2005-534048    Patent Document 3: Japanese Unexamined Patent Application Publication No. 2007-13026